If you are worried about your trip sitter taking advantage of you when you're on LSD then you should pick another trip sitter.
When using psychedelics your perception of the world changes drastically and in the worst cases you may start to become paranoid that your sitter has ill intentions among many other things. For this reason it is best to pick a person you trust very much as your trip sitter so they can talk you out of a bad trip, assure you that they care about you and that you're a good person.
Just be relaxed and in a familiar, safe environment and your trip should go fine. If you start freaking out just remember that you are on a drug and you'll be back to normal after it wears off. Have you and your trip sitter research the drug you are taking. Make sure the trip sitter learns what to do in the event you start having a bad trip.
The protocol for the trip sitter during bad trips usually just involves comforting the person and reminding them that they are just on a drug and they'll be safe and back to normal when it wears off. The trip sitter shouldn't talk down to or patronize the tripper, definitely don't talk to them like theyre a small child. Speak in a calm level headed way and just keep giving them consolation that everything is going to be alright.
Pick a place and time where you won't be bothered and you have no responsibilities to attend to. Feeling safe and comfortable is a good way to start a trip.